The present invention relates to a fuel control system for a vehicle powered by an internal combustion engine, and more particularly to a system for interrupting the fuel supply at deceleration of the vehicle and for resupplying fuel at a low engine speed.
In order to improve fuel consumption and emission control of an automotive engine mounted on a motor vehicle, a system for cutting off the fuel supplied to cylinders of the engine at deceleration to idle the cylinders has been proposed. Japanese Utility Model Publication No. 54-14826 discloses a fuel control system which operates to reduce the amount of the fuel supply to a very small value during the deceleration of the vehicle without cutting off the fuel, in order to ensure the reacceleration. However, the fuel supply during the deceleration does not contribute to fuel economy and emission control. Moreover, the small amount of fuel supply causes the air-fuel mixture to dilute, which will result in increase of NO.sub.x in exhaust gases.
Japanese Patent Publication No. 44-19485 discloses a fuel cut off system which operates to resupply the fuel when engine speed decreases to a predetermined value. However, when a large amount of fuel is suddenly supplied, the torque of the engine rapidly increases, which causes a sudden acceleration to give shock to the driver.